The present invention relates to a camera having a lens mount for mounting an interchangeable lens unit.
Generally, a camera (for example, a single reflex lens camera) has a lens mount for mounting an interchangeable lens unit. The lens mount and the lens unit respectively include a mount ring and a joint ring, which are mating with each other.
In order to transmit auto-exposure (AE) signals and auto-focus (AF) signals between the lens unit and a controller provided in a body of the camera, the mount ring is provided with several connector pins, while the joint ring is provided with several receptacles which receive the connector pins. The connector pins are arranged in a circumference (on the mounting ring) with certain intervals. When the lens unit is mounted to the lens mount, the connector pins and receptacles are electrically connected.
Recently, a driving motor (for example, a focusing motor or a zooming motor) is provided to the lens unit. Thus, it is necessary to provide additional connector pins and receptacles used for supplying power to the lens unit.
In order to minimize a space for the connector pins, it is preferred to arrange the connector pins for signal transmission and the connector pins for power supply on a same circumference. However, when a user rotates the lens unit to remove the lens unit from the lens mount, there is a possibility that the connector pins for power supply is unintentionally contact with the receptacles for signal transmission. In such case, power is unintentionally supplied to a circuit in the lens unit (via receptacles for signal transmission), which may damage the circuit.
In order to solve this problem, a recently developed camera is arranged to turn off the power supply when the lens unit is not mounted. In order to detect whether the lens unit is mounted to the lens mount or not, such camera has a sensor provided to a so-called lock-release-button. The button is arranged to release the lock of a lock mechanism (which locks the lens unit mounted to the lens mount) and is pressed while the user removes the lens unit from the lens mount.
However, since the button is generally provided to a front wall of a casing of the camera, the sensor is also located behind the front wall of the casing. Accordingly, if water penetrates into the casing of the camera (through a gap around the button), the sensor may get wet. Thus, there is a possibility that electric parts of the sensor get rusty, causing a faulty continuity.